1. Field of the Invention
The present invention relates to truck bed loading and unloading systems, and, more particularly, to adjustable truck bed lift systems for loading, transporting, and unloading vehicles and other objects.
2. Description of Related Art
Various systems for transporting loads with trucks have been known in the art. Specifically, load carriers have been described that are tiltable in order to receive and/or discharge a load from the ground or from platforms of various heights. A vehicle transporting apparatus is disclosed by Bubik (U.S. Pat. No. 4,795,303) that includes a platform pivotally mounted to the chassis of a truck. A powered actuator moves the platform to either a forwardly inclined or a rearwardly inclined position.
Nespor (U.S. Pat. No. 4,929,142) has described a vehicle carrier the comprises a tilting bed for mounting on the chassis of a towing vehicle. The tilting bed is supported by a pair of elongated beams and brace structures positioned beneath the bed.
Roberts et al. (U.S. Pat. No. 5,249,909) have disclosed a towing truck having an elevated deck that is hydraulically operated. In use, the deck slides along a pair of oppositely spaced rails that are pivotally secured to the framework of the truck.
Rear bumpers are mandated by the U.S. Department of Transportation to be at most 32 inches above the ground. As these structures can impede loading and unloading processes in vehicles having pivotable beds, it is desirable to be able to move the bumper out of the way of the bed. One such system, disclosed by Scharf (U.S. Pat. No. 4,410,207), describes a bumper structure having arm members pivotally attached to the tiltable load carrier. The bumper structure is automatically adjusted from an extended condition to a retracted condition as the tilting load carrier angularly moves from a horizontal position to its maximum angular position.
Another system, described by Matson (U.S. Pat. No. 4,516,902), teaches a bumper apparatus connected to a tiltable trailer, wherein the bumper is automatically positioned between a depending position and a raised position. In addition, Westbrook (U.S. Pat. No. 5,022,703) discloses a retractable rear bumper that is attached to shafts that are telescoped into tubes in order to move them against the bottom of the truck bed. Lutz et al. (U.S. Pat. No. 4,988,258) also describe a bumper apparatus that is pivotally mounted to an elevated chassis, wherein the bumper can be raised by a piston-style actuator.